title: The phenotype of MDM2 auto-degradation after DNA damage is due to epitope masking by phosphorylation.
abstract: It is widely accepted that DNA damage induces rapid degradation of MDM2 through phosphorylation, resulting in a transient reduction of MDM2 level. Elimination of MDM2 is a logical mechanism that stabilizes p53. This phenomenon has been reproduced by many independent studies and is frequently referenced. Here we present evidence that only phosphorylation-sensitive antibodies SMP14 and 2A10, but not other MDM2 antibodies, can detect robust down-regulation of MDM2 after DNA damage. Therefore, we conclude that DNA damage does not accelerate MDM2 auto-degradation. SMP14 and 2A10 are frequently used to detect human and mouse MDM2, respectively. While it is not clear whether the discrepancy is entirely due to the use of these antibodies, our results suggest that epitope masking by phosphorylation should be an important consideration when interpreting results of MDM2 analysis by SMP14 and 2A10.
authors.affiliation: Molecular Oncology Department, Moffitt Cancer Center; Tampa, FL USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Cheng
authors.forename: Jiandong
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D000906:Antibodies / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D004249:DNA Damage; D000939:Epitopes / Q000235:genetics*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D000906:Antibodies; D000939:Epitopes; D016159:Tumor Suppressor Protein p53; D051736:Proto-Oncogene Proteins c-mdm2